Pyridinium-p-toluenesulfonate

Pyridinium p-toluenesulfonate, r-BuOH or 2-butanone, reflux, 80-99% yield.This method is recommended for allylic alcohols. MEM ethers are also cleaved under these conditions. 

Me2C(OMe)2, DMF, pyridinium p-toluenesulfonate (PPTS). The use of PPTS for acid-catalyzed reactions has been quite successful and is particularly useful when TsOH acid is too strong an acid for the functionality in a given molecule. TBDMS groups are stable under these conditions. 

Pyridinium p-toluenesulfonate (PPTS), dihydropyran, CH2CI2, 20°, 4 h, 94-100% yield. The lower acidity of PPTS makes this a very mild method that has excellent compatibility with most functional groups. 

Pyridinium p-toluenesulfonate, EtOH, 22-55°, 1.2-2 h, 80-92% yield." These conditions were used to remove cleanly a TBDMS group in the presence of a TBDPS group. 

The wide applicability of the PK reaction is apparent in the synthesis of pyrroles, for example, 45, en route to novel chiral guanidine bases, levuglandin-derived pyrrole 46, lipoxygenase inhibitor precursors such as 47, pyrrole-containing zirconium complexesand iV-aminopyrroles 48 from 1,4-dicarbonyl compounds and hydrazine derivatives. The latter study also utilized Yb(OTf)3 and acetic acid as pyrrole-forming catalysts, in addition to pyridinium p-toluenesulfonate (PPTS). 

Treatment of 1 with p-methoxyacetophenone dimethyl acetal or a,/Fdimethoxystyrene, in the presence of pyridinium p-toluenesulfonate, gave the 2,3-acetal derivative. Although a new chiral center is generated in the product, a preference for a major isomer was observed (26). 

LDA = lithium diisopropylamide DMAP = 4-N,N-dimethylaminopyridine PPTS = pyridinium p-toluenesulfonate... 

The step 2 product (14.9 mmol) and pyridinium p-toluenesulfonate (0.477 mmol) were treated in 150 ml chloroform with 3,4-dihydro-2H-pyran (110 mmol) and the protected isolated. 

Tetrahydropyranilation of alcohols is an important process for the protection of hydroxyl groups. For this purpose pyridinium p-toluenesulfonate and bis(trimethyl-silyl) sulfonate have been frequently employed as mild catalysts. The apphcation of EGA catalysis is an effective alternative to protection and deprotection of hydroxyl groups The combinations, CH2CI2—LiClO4—Et4NC104 and MeOH—LiClO4 are applicable for the protection and deprotection step, respectively (34 35). 

Acetaldehyde triphenylmethylsulfenimine, CH3CH==NSC(C6H5)3 (1), m.p. 129-135°. Tritylsulfenimines can be prepared by reaction of aldehydes or ketones with triphenylmethanesulfenamide, (C6H5)3CSNH2, m.p. 119-122°, in CH2C12 in the presence of pyridinium p-toluenesulfonate.1... 

NMO NMP Nu PPA PCC PDC phen Phth PPE PPTS Red-Al SEM Sia2BH TAS TBAF TBDMS TBDMS-C1 TBHP TCE TCNE TES Tf TFA TFAA THF THP TIPBS-C1 TIPS-C1 TMEDA TMS TMS-C1 TMS-CN Tol TosMIC TPP Tr Ts TTFA TTN N-methylmorpholine N-oxide jV-methyl-2-pyrrolidone nucleophile polyphosphoric acid pyridinium chlorochromate pyridinium dichromate 1,10-phenanthroline phthaloyl polyphosphate ester pyridinium p-toluenesulfonate sodium bis(methoxyethoxy)aluminum dihydride (3-trimethylsilylethoxy methyl disiamylborane tris(diethylamino)sulfonium tetra-n-butylammonium fluoride f-butyldimethylsilyl f-butyldimethylsilyl chloride f-butyl hydroperoxide 2,2,2-trichloroethanol tetracyanoethylene triethylsilyl triflyl (trifluoromethanesulfonyl) trifluoroacetic acid trifluoroacetic anhydride tetrahydrofuran tetrahydropyranyl 2,4,6-triisopropylbenzenesulfonyl chloride 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane tetramethylethylenediamine [ 1,2-bis(dimethylamino)ethane] trimethylsilyl trimethylsilyl chloride trimethylsilyl cyanide tolyl tosylmethyl isocyanide meso-tetraphenylporphyrin trityl (triphenylmethyl) tosyl (p-toluenesulfonyl) thallium trifluoroacetate thallium(III) nitrate... 

Quaternary-salt formation can also occur, particularly at elevated temperatures, if the sulfonylation product has a primary sulfonyloxy group. Thus, 2,3-0-isopropylidene-l-0-tosyl-D,L-glyceritol readily reacts86 with hot pyridine to give the corresponding pyridinium p-toluenesulfonate ... 

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